Parker was born in Cortland, New York and practiced law in Kingston, New York. He served as Parker served as a justice of the Supreme Court of New York from 1885 to 1889. He later served as chief judge of New York Court of Appeals from 1897 to 1904.
Parker resigned as chief judge after receiving the 1904 Democratic Party nomination for the U.S. presidency. Division within his party over currency issues and the popularity of incumbent Theodore Roosevelt led to Parker's landslide defeat.